A common approach to continuously monitoring a person's health condition, for example heart rate, respiration rate, and the like, requires that the subject wear one or more sensors that are physically coupled to a stationary electrical mains-powered monitoring device. Another common approach is to couple the sensors to a wireless transmitter powered by a portable battery pack. Such approaches can be problematic.
For example, a healthcare provider may be interested in monitoring an infant's heart and respiration rate. However, tethering a baby to lengthy wired devices for continuous monitoring, as is usually done, can be difficult. Besides being uncomfortable, such wired monitors can be hazardous if the baby gets entangled in them. Moreover, monitors that are attached to cumbersome battery packs or mains powered processing units add to the discomfort of the infant.
Over the last decade, there has been a big push towards the development of wearable health monitoring devices. The underlying assumption is that wearable devices will allow for affordable round-the-clock monitoring, which will, in turn, enable early detection and prevention of many diseases. Heart rate monitors and electrocardiogram (ECG) devices are a group of devices that have received wide attention from the wearable devices community. However, research on ECG monitors has been focused on making better wearable sensors and integrating them with a minimal profile. To wirelessly transmit the cardiac information, a battery-powered solution is generally used, together with communication methods like Bluetooth and cellular technologies or prototype radio frequency (RF) transmitters. Batteries add to the size and weight of wearable systems, making them obtrusive and cumbersome.